The electrical industry uses a variety of insulating fluids which are easily available and cost effective. Examples are mineral oil, silicone fluid, and synthetic hydrocarbon oils used in transformers, power cables and capacitors. Examples of such fluids include those described in U.S. Pat. No. 4,082,866 issued Apr. 4, 1978 to Link, U.S. Pat. No. 4,206,066 issued Jun. 3, 1980 to Rinehart, U.S. Pat. No. 4,621,302 issued Nov. 4, 1986 to Sato et al., U.S. Pat. No. 5,017,733 issued May 21, 1991 to Sato et al. U.S. Pat. No. 5,250,750 issued Oct. 5, 1993 to Shubkin et al., and U.S. Pat. No. 5,336,847 issued August 9, 1994 to Nakagami, which are each incorporated herein by reference.
Many of these fluids are not considered to be biodegradable in a reasonable time frame. Some have electrical properties which render them less than optimal. In recent years regulatory agencies have become increasingly concerned about oil spills which can contaminate the ground soil and other areas. A biodegradable oil would be desirable for electrical apparatus such as transformers used in populated areas and shopping centers.
Vegetable oils are fully biodegradable, but the oils presently available in the market are not electrical grade. A few vegetable oils such as rapeseed oil and castor oil have been used in limited quantities, mostly in capacitors, but these are not oleic esters.
There is a need for a fully biodegradable electrical fluid. There is a need for electrical apparatuses which comprise such an oil. There is a need for a method of processing vegetable oil to electrical grade.